The present invention relates generally to electromagnetic directional control valves.
Such directional control valves are known in many embodiments and used for example in automatic transmissions of motor vehicles, for example to perform a gear change or to adjust pressure level of the pressure medium to the torque of the transmission to be actually transmitted. The directional control valves of this type must satisfy the requirements of an inexpensive construction and at the same time to provide precise and reliable operation over a long operational time.
A directional control valve is disclosed for example in the German patent document DE 42 37 681. This known directional control valve is relatively expensive to manufacture since the pole body and the controlling part are assembled to a single-part structural group which must be machined in a relatively expensive material-removing process. Furthermore, this construction is limited to directional valves which in currentless condition of the coil are closed and can not be transferred without problems to structural variants which are open in the currentless condition.